David McCorquodale, head of retail at KPMG, said: "Chilly winds blew up Scottish high streets in May as retail sales declined at rates not seen since 2012.

"The worst declines were in fashion and footwear, whose early spring revival took a setback as May's weather turned for the worse.

"There will be fingers crossed in the fashion trade for some sustained summer weather throughout June to boost sales before the holiday season, rather than be forced into heavy discounting.

"Outdoor living and DIY also suffered with the cooler weather and it was left to home furnishings and health and beauty to show resilience and growth.

"With the whole of the UK showing continuous growth in non-food sales, retailers will be keen to see Scottish consumers have the confidence to catch up and narrow the gap.

"Food sales continued to decline as deflation dominates the headlines. This is good news for consumers, who are taking advantage of a highly competitive market as grocers fight hard for share of wallet with promotional activity.

"For the retailers, they know hard work lies ahead over the summer months as Scotland will have less footfall without the repeat of last year's major sporting events hosted during the summer.''

Total food sales last month were 2.1% down on May 2014, when they had decreased 2%.

Adjusted for the estimated effect of online sales in Scotland, total non-food sales decreased by 2.4% over May 2014, when they had increased by 0.5%.

This is the deepest decline since the report began measuring the online effect in December 2012.

David Lonsdale, director of the Scottish Retail Consortium, said: "Lower prices in shops and at the petrol pump and a more optimistic outlook for jobs and wages growth have yet to translate into increased consumer spending at shop tills.

"Retailers will be looking to the Chancellor in his upcoming summer Budget for measures to help consumer spending take wing.''